1. Field of the Invention
Methods and apparatuses consistent with the present invention relate to intra encoding/decoding an image.
2. Description of the Related Art
In video compression methods, such as MPEG (Moving Picture Experts Groups)-1, MPEG-2, and MPEG-4 H.264/MPEG-4 Advanced Video Coding (AVC), a picture is divided into a plurality of macro blocks in order to encode or decode the picture. Next, each of the macro blocks is encoded using inter prediction (temporal prediction) and intra prediction (spatial prediction). Next, an optimal encoding mode is selected in consideration of the data sizes of the encoded macro blocks and the extent of degradation of the original macro blocks, and the macro blocks are encoded according to the optimal coding mode.
In intra prediction, encoding is performed using pixels spatially adjacent to the current block within a current picture without using a reference picture. First, a predicted block of the current block that is to be encoded is generated using the values of the adjacent pixels, and only the difference between the pixel values of the predicted block and the current block is encoded. An intra prediction mode is largely classified into a 4×4 intra prediction mode, an 8×8 intra prediction mode, and a 16×16 intra prediction mode according to luminance components, and an intra prediction mode according to chrominance components.